Operators Manual

Table Of Contents
Once Cruise Control is enabled and you reach your road speed, press the SET
Switch to activate Cruise Control. The cruise light will come on. To increase road
speed toggling the switch will result in a one mile-per-hour (1.6 kph) increase or
decrease in vehicle speed. If Cruise Control has been disabled, toggling the
RSM/ACC Switch restores the vehicle to the previously set cruise speed. , press the
RSM/ACC Switch. To reduce road speed, press and hold the SET/CST Switch until
the lower speed is reached.
Cruise Control can be overridden at any time with the throttle pedal if the vehicle is
operating at less than the programmed Max Road Speed.
Cruise Control is deactivated by slightly pressing the service brakes, clutch pedal,
or trailer brake. The ON/OFF Switch will also deactivate Cruise Control.
Cruise Control will maintain vehicle speed even on upgrades, unless power
requirements demand a downshift. If the Cruise Control/Engine Brake function is
turned ON, the Cruise Control will limit your speed on downgrades. Most likely,
Cruise Control will feel stronger than driving with the accelerator pedal because of
the instantaneous and wide-open throttle response. That's why Cruise Control use is
not suggested during slippery driving conditions.
Use Cruise Control after downshifting on a hill to pull the hill. Hitting the
RSM/ACC Switch (not the SET Switch) will keep the truck accelerating in the
lower gears up to the rated engine speed.
CAUTION: LOSS OF VEHICLE CONTROL
To avoid injury from the loss of vehicle control, do not use cruise
control under these conditions:
When it is not possible to keep the vehicle at a constant speed
(on winding roads, in heavy traffic, in traffic that varies in
speed, etc.).
On slippery roads (wet pavement, ice-or snow-covered roads,
loose gravel, etc.).
Cruise Control will maintain the set speed under normal road and load conditions.
It cannot limit vehicle speeds on down grades if available engine braking effort is
exceeded, nor can it maintain speed on upgrades if power requirements exceed
engine power capability.
Cruise Control will disengage below 1000 rpm or 20 mph (32 kph) road speed.
When using Cruise Control, if you want to pull the engine below 1000 rpm,
remember to hold the accelerator pedal to the floor to keep the engine pulling at
wide-open throttle. The engine will pull down to about 1050 rpm.
Remember:The electronic data programmed into the DDEC system will not allow
you to hurt or over fuel the engine at low or lug engine speeds. There is enough oil
pressure to withstand hard pulls at low engine speeds.
Cruise Control may also be programmed to permit fast idle using the Cruise
Control switches.
Detroit Diesel Electronic Controls (DDEC) System
74 All information subject to change without notice.
Copyright © 2022 DETROIT DIESEL CORPORATION DDC-SVC-MAN-0189